This invention relates to surgical saw blades and, more particularly, to an oscillatory surgical saw blade having an adjustable cutting depth stop for use with a power operated surgical saw.
Various techniques have heretofore been utilized by surgeons in cutting and removing surgical casts made of plaster or, more recently, tougher plastic dressings and casts formed of fiberglass. For this purpose, saw blades either rotary or oscillatory in nature have been utilized with power operated surgical saws which, unless means are provided for limiting the depth of cut, pose a danger to the patient. With the oscillatory type of surgical saw, the saw blade performs short, very quick, oscillating motions along a small circular arc at frequencies between 12,000 and 14,000 oscillations per minute. These very short stroking motions will not produce significant cutting effect as the saw temporarily contacts skin or dressing material, but prolonged contact with the skin can cause abrasion and/or burning. However, there is a considerable cutting effect once the saw gets into contact with solid material, such as a plaster cast. Thus, it is desirable that the saw blade be provided with a stop to limit the depth of cut so as to avoid contact with the body limb or portion that is encompassed by the cast.
An oscillatory electrical plaster saw, Model OK7000 available from Ortopedia, a German company, has a cutting depth stop in the form of a flat metal dish which is secured eccentrically with respect to the saw blade to the connector or shaft of the saw. In assembling the saw blade and depth stop onto the shaft, first the saw blade and then the dish-like depth stop are slid onto the toothed shaft and then secured by tightening a cap screw; firm tightening, which requires a socket head wrench, is imperative to prevent destruction of the teeth of the saw blade. The shaft of the saw passes through an off-center hole in the circular dish-like stop such that the lip of the "dish" serves to set the depth of cut in accordance with the rotational position of the dish relative to the selected arcuate cutting portion of the saw blade. Once assembled, the depth of cut can be adjusted only by loosening the cap screw, which requires a wrench, turning the dish relative to the saw blade, and again firmly tightening the cap screw. The need for a tool, and the necessity of allowing the depth stop to cool before adjustment can be effected, makes this saw very inconvenient to use, particularly when depth adjustment is required during the course of the cast removal procedure.
Another form of cutting depth stop for a surgical saw blade is disclosed in U.S. Pat. No. 4,461,296 wherein guard elements are physically secured, as by welding, to opposite sides of a saw blade, the elements being positioned at a fixed predetermined distance from the saw teeth. The guard element may be symmetrical and concentrically located with respect to the center of the blade to provide a constant limitation to the depth of cut, or may be eccentric and/or nonsymmetrical whereby when in oscillating use, different portions of the blade are capable of different depths of cut. The depth of cut for a particular portion of the blade is not adjusable, and a change in depth of cut can be effected only by the user rotating the power tool and the attached saw in his/her hand.
It is an object of the present invention to provide an improved oscillatory surgical saw blade for use in conjunction with a power operated surgical saw, which blade is designed to permit ready and convenient adjustment of the depth of cut.
Another object of the present invention is to provide an improved oscillatory surgical saw blade for use in conjunction with a power operated surgical saw, which blade is designed to permit adjustment of the depth of cut without disconnecting the blade from the saw and without the need for tools.